This application pertains to the art of mowing machines for grass and brush. More particularly, the invention relates to wide sweep or wing mowers which are designed to be towed by tractors or other vehicles. The invention finds particular application in mowers for maintaining the grass medians of highways and will be described with particular reference thereto. It is to be appreciated, however, that the invention has broader applications including machines for maintaining and reclaiming large expanses of grasses, weeds, light brush, and trees up to about a 5 inch diameter.
Numerous tractor towed mowing devices or trailing mowers are known in the art, note for example U.S. Pat. No. 2,952,961, issued September, 1960 to J. F. Engler, U.S. Pat. No. 3,400,521, issued September, 1968 to Caldwell, U.S. Pat. No. 3,527,032, issued September, 1970 to Wood. These prior art trailing mowers included a central mowing assembly which was supported by wheels toward the rear and adapted to be connected with the tractor at the front. A first and a second side or wing mowing assembly was hingedly connected to either side of a mowing central assembly. The hinged interconnection permitted the wing assemblies to be folded vertically to reduce the width of the towed mower and facilitate its transportation. The central and side assemblies each included a cutting blade which was connected by a mechanical gear train with a power take off of the tractor.
Others have suggested replacing the mechanical drive of trailing mowers with a hydraulic drive system, note for example U.S. Pat. No. 3,729,910, issued May, 1973 to Hardee and U.S. Pat. No. 4,308,713, issued January, 1982 to James. With the use of hydraulic drive systems, came the need for cooling the hydraulic fluid to inhibit high temperature hydraulic fluid breakdown. One solution was to use a sufficiently large reservoir, that the hydraulic fluid remained relatively cool. Another solution was to install a heat exchanger on the tractor, reservoir, or mower. One such heat exchanger has been on sale and in public use since 1976 by the Triumph Machinery Company of Hackettstown, New Jersey. In the Triumph heat exchanger, the upper deck of the mower adjacent the cutting blade served as the base of the heat exchanger. A generally U-shaped channel and end plates were welded to the upper deck to define a relatively flat, elongated heat exchanger through which the hydraulic fluid was channelled. In principle, the updraft created by the rotatory motion of the cutting blades would circulate cooling air against the deck and heat exchanger. Another mower in which the deck functioned as the lower wall of the heat exchanger is illustrated in the above referenced James patent.
One of the problems encountered in utilizing the upper deck as a wall of the heat exchanger is that wet grass forms a mat or cake between the deck and the cutting blades. Because grass and brush hold moisture and dew, the cuttings are frequently damp. The damp cuttings form a fiberous mat on the underside of the deck which functions like fiberglass or glass wool insulation. This mat is effective insulation which inhibits the hydraulic fluid from dissipating heat through the deck. Further, constructing the heat exchanger integrally with the deck inhibits air circulation around the heat exchanger and completely blocks air circulation between the deck and the heat exchanger.
The present invention contemplates a new and improved trailing mower which has an improved heat exchanger design and an improved side wing lifting mechanism that overcomes the above referenced problems and others.